1. Technical Field
This invention relates to medical devices in general, and specifically to grafts positionable intraluminally for repairing aneurysms or other vascular defects in humans and animals.
2. Background
Aneurysms are caused by weakening of a vessel wall which results in the outward ballooning of the wall under the pressure of flowing blood. Aneurysms are more prevalent in men than in women, and are more common with advancing age. Prior to the development of technology to repair the bulging blood vessel, aneurysms posed a fatal threat to those who developed them. Even with the early development of repair procedures, significantly invasive surgery was required to access the aneurysm. Today, graft structures have been developed which allow insertion and delivery of the graft to the point of the aneurysm using less invasive procedures.
Known intraluminal graft structures generally comprise a tubular graft, expansion means for deploying and positioning the graft in the vessel and anchoring or attachment means for keeping the graft in place within the vessel. Many varying types of expansion means have been disclosed, including those described in U.S. Pat. No. 4,140,126 to Choudhury (expandable ring positioned at open end of graft); U.S. Pat. No. 4,776,337 to Palmaz (a mesh-like tube); U.S. Pat. No. 5,123,917 to Lee (zig-zagged expandable ring); and U.S. Pat. No. 5,151,105 to Kwan-Gett (helically-coiled spring). Means have also been described for providing longitudinal support to the graft, including those means described in U.S. Pat. No. 4,562,596 to Kornberg (a plurality of steel struts) and U.S. Pat. No. 5,151,105 to Kwan-Gett (diametrically spaced adjustable ribs).
Additionally, various means for attaching the graft to the vessel have been disclosed. Most frequently, hook, barb or pin means are described and used, including the means described in U.S. Pat. No. 4,140,126 to Choudhury (a plurality of pins); U.S. Pat. No. 4,562,596 to Kornberg (a plurality of barbs; and U.S. Pat. No. 5,151,105 to Kwan-Gett (staples). In some instances, the hook or barb means are attached to the expandable means as described in U.S. Pat. No. 4,140,126 to Choudhury and U.S. Pat. No. 5,104,399 to Lazarus. U.S. Pat. No. 4,577,631 to Kreamer discloses use of an adhesive covering the entire outside of the graft to provide adherence of the luminal intima to the graft.
The most commonly used intraluminal graft structures have hooks or barbs which pierce into or through the wall of the vessel to anchor the graft to the vessel above the aneurysm. That is, most, if not all, currently used intraluminal grafts are supported in the vessel upstream from or above the disease condition. However, hooks or barbs may damage the vessel, particularly where the vessel is weakened already by an aneurysm or other disease condition. Additionally, there are instances when the condition of the vessel may make it impossible or imprudent to use a graft device having hooks or pins, such as the existence of calcium deposits. Such conditions may also limit the usefulness of adhesives.
Thus, it would be advantageous to provide an intraluminal graft which is adapted for use in vascular repair under any conditions, but particularly under conditions which limit or prevent the use of intraluminal grafts having hook, pin, barb or staple attachment means. That is, it would be advantageous to provide an intraluminal graft which is structured to be supportable from a position downstream or below the disease condition to thereby eliminate the need for hook, pin, barb or staple anchoring means. Such structure would allow the placement and positioning of a graft within a diseased vessel when the condition or morphology of the vessel prevents use of barb-type attachment means. It would also be advantageous to provide an intraluminal graft structured to be flexible and adjustable to thereby facilitate insertion and placement of the graft within a vessel which displays abnormal morphology.